1. Field of the Invention
The present invention relates to a Light Emitting Diode (LED) package capable of preventing damage to an LED due to electrostatic discharge, and more particularly, to an LED package having a protective function against electrostatic discharge, in which a Micro Electro Mechanical Systems (MEMS) switch operable to electrostatic force is provided to continuously protect an LED from excessive current due to electrostatic discharge.
2. Description of the Related Art
Having superior physical and chemical properties, a nitride semiconductor using nitride such as GaN has become popular as core material for photoelectric material and electric devices recently. Particularly, the nitride semiconductor light emitting device is capable of generating a range of light including green, blue and ultraviolet ranges, and with its luminance rapidly enhanced by the recent technological development, it has been extensively applied to the fields such as all-natural color electric bulletin boards and illumination apparatuses.
In general, a nitride semiconductor light emitting device has a disadvantage in that it is very vulnerable to static electricity compared with the semiconductors composed of other compounds such as GaP or GaAlAs. For example, the nitride semiconductor light emitting device can be destroyed by constant voltage in forward direction of about hundreds of volts (100V or higher), and also by constant voltage in backward direction of about tens of volts (30V or higher). Such vulnerability to constant voltage can be a cause of damage to the LED when handling the nitride semiconductor light emitting device. Therefore, various researches have been conducted to overcome the vulnerability of the nitride semiconductor light emitting device to static electricity. In relation to this, U.S. Pat. No. 6,861,677 (entitled “Package of Light Emitting Diode with Protective Element,” assigned to United Epitaxy Co., Ltd.) discloses an LED package having a combined structure of a nitride semiconductor light emitting device and a Zener diode on a single substrate.
FIG. 1(a) illustrates the conventional LED package disclosed in U.S. Pat. No. 6,861,677. With reference to FIG. 1(a), in the LED package 10 disclosed in U.S. Pat. No. 6,861,677, an n-electrode 111 is connected to a p-electrode 121 of the Zener diode 12 through a conductive bump 151, and a p-electrode 112 of an LED 11 is connected to a conductive heat-radiation structure 14 through another conductive bump 152, and the conductive heat-radiation structure 14 and the n-electrode 122 of the Zener Diode 12 are adhered to a substrate 13 for electrical connection.
The structure of the conventional LED package 10 described above has a circuit structure as shown in FIG. 1(b). That is, an anode of the LED 11 is connected to a cathode of the Zener diode 12, and a cathode of the LED 11 is connected to an anode of the Zener diode 12 in parallel. Therefore, when both electrodes of the LED 11 are applied with backward voltage, then the Zener diode 12 becomes applied with forward voltage, thereby current runs through the Zener diode 12, not through the LED 11. In addition, in case when forward voltage is applied to both electrodes of the LED, if voltage lower than the breakdown voltage of the Zener diode 12 is applied, current runs through the LED 11, and light emission takes place. If forward voltage higher than the breakdown voltage of the Zener diode 12 is applied, the Zener diode 12 breaks down, allowing all currents to run through the Zener diode 12. Therefore, the conventional LED package uses the Zener diode 12 to prevent current by excessive voltage applied forward and backward by static electricity from running through the LED 11, thereby preventing damage to the LED due to static electricity.
However, the conventional LED package which protects the LED from electrostatic discharge uses the Zener diode 12, and thus once excessive current has run through the Zener diode 12, the Zener diode 12 can no longer be operated, no longer performing the protective function against electrostatic discharge. In other words, the conventional LED package having a protective function against electrostatic discharge can perform the protection function only once, and cannot perform repeatedly, and thus the LED remains vulnerable to the exposure to excessive current due to electrostatic discharge.